Motor fuel



Patented July 1, 1941 FFICE MOTOR FUEL Ulric B. Bray, Palos VerdesEstates, Calif, as-

signor to Union Oil Company of California, Los Angeles, Calif., acorporation of California No Drawing. v Application January 8, 1937,Serial N0. 119,623

7 Claims.

This invention relates to motor fuels of the liquid type and especiallymotor fuels consisting primarily of cracked products such as crackedpetroleum distillates.

The specific object of the invention is to add to fuels constituentsderivable, at least in part, from petroleum stocks which constituentsare adapted to overcome varnish and resin formations and prevent thedeposition of gums and the like whereby to prevent or at least minimizethe sticking of valves and rings in internal combustion engines. Thisapplies particularly to cracked fuels which especially tend to thedeposition of such gummy and resinous materials.

Primarily the invention resides in a liquid fuel, especially a crackedfuel, containing a small quantity, sufiicient to overcome the aboveobjections, of aromatic constituents of the type derived from petroleumstocks by means of selec-- tive solvents, such as the well knownEdeleanu extracts obtained by treatment of various petroleum stocks withliquid sulfur dioxide. The invention also extends to kindred extractsobtained by other solvents or in other ways. The invention includesfurther the addition of a small quantity of another constituent in theform of a high boiling oxygenated gum or resin solvent of the type ofdibutylphthalate, including diamylphthalate, diphenyloxide,chlorodiphenyl oxide, and methyl abietate, oleate and laurate. Whiledibutylphthalate is preferred, with the other above mentioned solventsreceiving next choice, other high boiling gum solvents may sometimes besubstituted. Such possible substitution may include other high boilingesters and ethers, as well as alcohols, ketones, acids and aldehydes andkindred high boiling oxygenated gum and resin solvents. These, in turn,may contain also substituted constituents such as chlorine, sulfur,phosphorus, arsenic or selenium for the purpose of increasing oilinessor film strength where lubricated surfaces com in contact with the fuelor constituents thereof, and also for combatting corrosion. Theinvention also resides in a cracked or gum or resin forming fuelcontaining a small quantity of such a high boiling oxygenated gumsolvent.

The aromatic solvent extract fractions from petroleum of the typerepresented by the abovementioned "Edeleanu extracts, constitute inthemselves an oil fraction of considerable lubricating value in additionto the plasticizing or softening functions which they exert upon gum,resin and varnish-type formations. Thus, the invention may be furtherstated as comprising a motor fuel of 'the liquid type, such as gasolineand Diesel engine fuel, especially where the fuel is a cracked fuel,containing a small quantity of the aromatic type lubricating oilfraction adapted to soften or plasticize resin and varnish deposits,together with a small quantity of a high boiling oxygenated gum solventof the type represented by dibutylphthalate. The small amounts to beadded are in the order of 1% to 2% and less of the additive materials.For example about 0.3% of a mixture of one part of dibutylphthalate andtwo parts of an appropriate aromatic solvent-extract fraction of thetype represented by liquid sulfur dioxide extracts has been satisfactoryin cracked gasoline. The high boiling oxygenated gum solvent serves todissolve or loosen gums, resins and the like and the aromaticlubricating extract fraction serves to maintain all such gum and varnishdeposits in a plasticized condition upon or about the parts of aninternal combustion engine, particularly valves, rings and fuel passageswhere such deposits tend to accumulate. Thus, the invention may bestated also as residing in a motor fu'el otherwise tending to depositgums, resins and varnish-like materials in the fuel induction system andupon valves and rings, containing a small quantity in the order of 2%,1% orless of an aromatic type or solvent-extract lubricating oilfraction as a plasticizer of said materials and a high boiling solventfor such materials.

In practising the present invention a suitable aromatic-type lubricatingoil fraction may be obtained by any selective solvent extraction processapplied to petroleum stocks containing the required aromatic-typeconstituents. In employing such a lubricating or extract fraction, thesame is preferably combined with a high boiling gum solvent. Thesematerials may, for example, be combined in approximately equalquantities, and I have found a very desirable blend to consist of aboutone-third of a high boiling solvent and about two-thirds of a solventextract from spray oil or light lubricating oil fractions such as liquidsulfur dioxide extract. These proportions, of course, may be modified solong as the required functions are obtained. This blend of the gumplasticizer and of the high boiling gum solvent is added to thegasoline, preferably only in such quantities as are necessary toovercome the resin or varnish deposits normally occurring in some typesof gasoline when used in internal combustion engines.

The gasolines customarily employed which tend to create such depositsare the well known cracked from lubricating oils.

gasolines and for this purpose I have found less than 1% is ordinarilyadequate. For example, 0.3% produces a very satisfactory motor fueladapted to accomplish the ends here sought. A smaller quantity may, ofcourse, be employed with less advantageous results and likewise a largerquantity up to around 1% or 2% may be added where a particularlyrefractory motor fuel is concerned. The high boiling solvent preferredis dibutylphthalate and such constituent was used where 0.3% of themixture was added to the gasoline.

With respect to the aromatic-type lubricating oil fraction a liquefiedsulfur dioxide extract, commonly known as Edeleanu extract, has beenfound very desirable, especially where such an extract from a spray oilstock has been mildly treated as with sulfuric acid to eliminate themore readily reactive and unsaturated constituents (as well as anytending toward a heavy or tarry nature) so as to leave a more aromaticfraction containing less reactive constituents and therefore morestable. In employing an extract of this type, it will be understood thatit is preferable that the same be obtained from a stock which will yieldan appropriate fraction in a suitable boiling range with respect to thegummy, resinous and varnish-like constituents which are to becontrolled. For this reason, extracts from spray oil stocks are highlydesirable inasmuch as they possess appropriate boiling ranges.Obviously, kindred results may be obtained with extracts of somewhatlower or higher boiling ranges, although these are often not to bepreferred. 'For the purpose of removing the more readily reactive andmore highly unsaturated constituents, a light sulfuric acid treatmentmay be given, for example by treating with 75 to 100 lbs. per barrel ofgasoline of a 98% sulfuric acid at controlled temperatures around 100 F,but not greatly exceeding that temperature and with a limit preferablynot exceeding 110 F. Preferably this acid treatment is given in two orthree dumps, for example three dumps of 25 lbs, per barrel each. Afterseparation of the sulfuric acid and contained reaction products, theremaining portion of the sulfur dioxide extract, which usually is themajor portion of such extract, is neutralized with an aqueous solutionof sodium hydroxide, washed with hot water, and

preferably clay treated. It is then ready to be employed for thepurposes of the present invention.

Again, where liquid sulfur dioxide treatment of petroleum fractions iscarried on in stages,

' that extract from a suitable stage may be employed, for example thatextract from an intermediate stage. By employing extracts from intermediate stages or from later stages of plural stage treatments, itwill be possible to use extracts from heavier petroleum fractions suchas This will be particularly true of extracts obtained from thetreatment of light lubricating oils by various known solvent extractionmethods, for example extraction by liquid sulfur dioxide and benzolmixtures. Here an intermediate or light extract may be found which willbe suitable and if these extracts still contain the constituents whichare too reactive, these may be further treated with an appropriatesolvent, for example sulfuric acid as above described, to yield thefraction desired.

Extract fractions from petroleum stocks of the types herein indicated,including Edeleanu extracts are largely soluble in liquid sulfurdioxide, and are known to be complex mixtures of aromatic andunsaturated hydrocarbons, including alkylated naphthalenes, mono-cyclicand condensed ring compounds as well as complex erally preferred in thepresent instance) may have a content of about 2.5%;

As above indicated, extracts usable here are not limited to liquidsulfur dioxide extracts but may be those obtained from other solventextraction processes, such as those employing phenol, furfural,dichlorethyl ether, chloraniline, nitrobenzol, acetone, chlorphenol,cresylic acid and crotonal-dehyde. The methods of conducting thesesolvent extractions and the amount of material employed are Well knownin the industry and need not be here described. It will be sufficient tosay that around one to two volumes of solvent per volume of oil arecommonly employed in countercurrent extraction and that the temperaturesvary, according to the solvent, between about -l0 F. and up to 125 F.,being governed in part by the extent of extraction desired. For example,the average treating temperatures for liquid sulfur dioxide would bearound 30 F, and for liquid sulfur dioxide-benzol mixtures around 10 F.

As above indicated, a suitable solvent extract having been segregated,the same is mixed with an equal quantity of a high boiling oxygenatedgum solvent, or two or three parts of one of these agents may beemployed to one part of the other and the-resulting mixture blended withthe gasoline tending to gum, the amount of added material being within arange of perhaps 0.1% to about 2% as may be required adequately toplasticize or to dissolve and maintain in plastic condition the gummyand varnish-like materials and prevent their accumulation in fuelinduction passages and upon valvesand rings to such an extent as toproduce incipient sticking thereof. The beneficial results hereof may beobtained by using extract from any light or medium viscosity lubricatingoil, but I find that the more aromatic type materials, such as obtainedfrom lighter fractions in the spray oil classification, which materialsare characterized by relatively low A. P. I. gravity and high viscositygravity constant, are preferable because of their greater efliciency andcapacity to plasticize the deposits from the liquid fuels mentioned. Thehigher the gravity and the more parafiinic the nature, the higher willbe the percentage of dibutyl phthalate or other gum solvent required.Appropriate extracts have an-A. P. I. gravity range from about 10 to 20and a viscosity of 50 to 150 seconds Say bolt Universal at F.

As a specific example of a suitable extract fraction and a method ofobtaining it,'I have extracted a spray oil stock having a viscosity of60 seconds Saybolt Universal at 100 F. and an A. P. I. gravity of 23.5,with liquid sulfur dioxide to yield an extract. (after expulsion of thesulfur dioxide) having a gravity of 14.6 A. P. I. and a viscosity ofseconds at 100 F. This extract was then treated with 25 lbs. of 93%sulfuric acid and 75 lbs. of 98% sulfuric acid per barrel at about 95F., with a recovery of about 75%. The acid-treated extract, afterneutralization had a gravity of 16.4 A. P. 1., a viscosity of 80 secondsSaybolt Universal at 100 F., and a deOng number of 33. This extract wasused for purposes of the present invention. The specifications for thestock, the sulfur dioxide extract, and the acid treated extract are:

,While I have shown that desirable plasticizing materials areconveniently obtained by solvent extraction of petroleum oil fractionssuch as lubricating and spray oil stocks, similar materials, as regardsboth physical characteristics and plasticizing action can be obtainedelsewhere, such as from certain appropriate fractions of cracking stillproducts. For example, a cracked gas oil fractionwas obtained bydistillation between 575 F. and 725 F. from a cycle stock from arecycling cracking operation on a naphthenio ming compounds, such asvapor phase treatment with adsorbent earth or with zinc chloridesolutions. k 1

It is observed that this invention does not constitute one of theso-called anti-oxidan processes where anti-oxidants are added, althoughit can be used in conjunction with and in addition type gas oil underliquid phase' cracking conditions. Such fraction was treated with 120lbs. 98% sulfuric acid per barrel and neutralized, and yielded amaterial of about 14 A. P. I. gravity with a viscosity of 75 secondsSaybolt Universal at 100 F. This extract was quite similar to the acidtreated sulfur dioxide extract above described. Obviously other kindredtypes also may be employed.

The oxygenated gum solvents required will of course have a boiling pointhigh enough so that they will be able to perform their desired function.Appropriate boiling points are in the general range of 550 F. orthereabouts and above at atmospheric pressure as represented by thespecific materials herein mentioned.

The invention is applicable to all varieties of motor fuel tending tocause difficulty from gum deposits, and the amount of the mixture ofaromatic plasticizer and high boiling gum. solvent as well as the ratioof aromatic plasticizer to gum solvent is best regulated in accordancewith the gum forming tendency of the gasoline. For an untreated crackedgasoline which gave 260 miligrams of gum by the well known copper dishtest, 0.8% of a 75-25 mixture of dibutyl phthalate and treated spray oilextract was used. The same gasoline after treatment with one pound of95% H2804 per barrel and redistillation with steam gave a copper dishgum test of 90 milligrams per 100 ml. Then only 0.4% of a 75-25mixtureor 0.6% of a 50-50 mixture of dibutylphthalate and treated spray oilextract was required for successful use, or in other words, a very muchsmaller proportion of dibutyl phthalate. After treatment with 3 lbs. of95% H2804 and redistillation, the gasoline showed a copper dish gum testof milligrams, and was successfully treated with 0.3% of a 2-1 mixtureof spray oil extract and dibutylphthalate. Similar results are obtainedwith other methods of gasoline treatment prior to adding the anti-gumtoanti-oxidants.

It is to-be understood that these disclosures are intended to be onlyillustrative of the generic invention, it being obvious that numerousvaria tions not herein indicated may be developed by those skilled inthe art.

I claim:

1. A motor fuel containing constituents normally tending to producegummy and resinous deposits in internal combustion engines containing asmall quantity of high boiling oxygenated gum solvent of thedibutylphthalate type together with a small quantity of a solventextract from petroleum adapted to plasticize said gummy and resinousdeposits to minimize sticking of valves and rings, said solvent extracthaving a gravity at least as heavy as about 16.4 A. P. I.

2. A motor fuel containing constituents otherwise tending to deposit gumand resinous materials in internal combustion engines and containing asmall quantity of a mixture of a high boiling oxygenated gum solvent ofthe dibutylphthalate type and an aromatic extract fraction frompetroleum stock free from heavy tarry and resinous and gum-formingconstituents, said mixture being present in quantity adapted toplasticize said gummy and resinous constituents and to minimize thesticking of rings and valves, said extract fraction being at least asheavy as about 16.4? A. P. I.

3. A motor fuel according to claim 2 wherein solvent and plasticizingagents are added in a quantity suflicient only to avoid valve and ringsticking in internal combustion engines and the solvent isdibutylphthalate.

4. A motor fuel comprising a gasoline tending to form gums and resins, asmall quantity of dibutylphthalate, and a small quantity of an aromaticextract from petroleum stock of intermediate boiling range, thedibutylphthalate and extract fraction being employed in small quantitlesin the order of less than about 2%.

5. A motor fuel comprising a liquid fuel containing constituents whichtend to gummy and resinous deposits in internal combustion engines. asmall quantity of dibutylphthalate and a small quantity of an aromaticsolvent extract petroleum fraction, at least as heavy as about 16.4" A.P. I.

6. A motor fuel comprising a cracked fuel, a small quantity ofdibutylphthalate and a small quantity of sulfur dioxide extract fractionfrom a petroleum stock of intermediate boiling range.

7. A cracked gasoline containing asmall quantity of a high boilingoxygenated gum solvent of the dibutylphthalate type and a small quantityof an aromatic solvent extract fraction from petroleum stock, suchfraction being largely soluble in liquid sulfur dioxide and being freefrom resinous and tarry constituents and from highly reactiveconstituents, the gum solvent and the extract fraction being employed insmall quantities to minimize tendency toward valve and ring sticking ininternal combustion engines, said extract fraction having a gravitybetween 14 and 17 A. P. I.

ULRIC B. BRAY.

